The present invention is directed to a printing form having a surface which has inorganically bonded silicon and a pattern composed of hydrophilic and hydrophobic regions, the hydrophilic regions having a first chemical state and the hydrophobic regions having a second chemical state that differs from the first state. The present invention is also directed to a method for modifying the wetting properties of a printing form having a surface which has inorganically bonded silicon, the surface being brought into a first chemical state having a first wetting property, and a portion of all regions of the surface being brought into a second chemical state having a second wetting property by modifying the chemical terminal groups of the surface.
From U.S. Pat. No. 3,678,852, a printing form is known which is coated with an amorphous semiconductor. It discusses using a laser beam to change the disordered amorphous state of the semiconductor into a more highly ordered crystalline state. In the crystalline state, the semiconducting surface is rougher so that the reordering of the semiconducting surface results in liquids adhering better in the region of the rougher surface than in the amorphous smooth regions. A printing form produced in accordance with this method is limited by the minimum size of the crystalline regions.
From the document WO 00/21753, it is known that a printing form which has a surface having silicon can be brought into a first chemical state having a first wetting property and into a second chemical state having a second wetting property. The local wetting property, thus the local hydrophilic or hydrophobic wetting property of the printing form, can be controlled by altering the chemical terminal groups of the surface having correspondingly different electronic properties. For this purpose, a surface having a first chemical structure is produced, which preferably has an essentially uniform hydrophilic or hydrophobic wetting property. This surface is then converted in localized areas by a localized modification of the chemical structure (terminal groups) into the respective other state of the wetting property, thus from hydrophilic to hydrophobic or from hydrophobic to hydrophilic.
In a preferred specific embodiment, silicon is selected as a semiconductor in the document WO 00/21753. The surface is first brought into a hydrophobic state, SiH, SiH2 and/or SiH3 groups being present at the surface. To modify the hydrophobic behavior, the hydrophobic terminal group is then exchanged locally, i.e. in individual regions, for a hydrophilic terminal group or converted into such a group, so that, for example, SiOH, SiOSi and/or SiO terminal groups replace the hydrophobic terminal groups.